Abstract The investigation of microfluidics heat transfer in recent years has been of great interest to researchers. In studies to improve the thermal performance of micro-devices, the use of nano-fluids, geometric corrections and other parameters have been investigated. In addition to examining the heat transfer of cooling systems, the research of thermodynamics second-law of these systems has been widely studied in recent years. In this study, thermodynamics second law and heat transfer of non-Newtonian nano-fluid in a micro-channel with distributing variable temperature on the wall, the presence and absence of porous blocks and slip velocity with finite volume method (SIMPLE algorithm) have been investigated. Non-Newtonian nano-fluid contains water-CMC as the basis fluid and volume fraction of 3% and 4% nano-particles of TiO2. The current study is reviewed in two sections in the Reynolds number (10−100) and nano-particles volume fraction (3–4). In the first section, it investigates the influence of slip velocity and compares first and second-order models with different slip factor (0–0.1) on heat transfer, fluid flow, entropy generation and exergy losses. The outcomes present that the slip velocity of the first-order increases the mean Nusselt number in the range of 2.02% to 12.48%, and this range is 1.91% to 7.52% for second-order. Also, the first-order and second-order slip velocities reduce the generation rate of frictional entropy by a maximum of 76.2% and 67.43%, respectively. The rate generation of thermal entropy and exergy losses exhibits variable behaviour with Reynolds number. In the second section, the Darcy number (5 × 10−3–5 × 10−5), porosity (0.75–0.95) and thermal conductivity ratio (1–15) with first-order slip velocity are examined. The Nusselt number increases locally by reducing, reducing and enhancing the Darcy number, porosity and thermal conductivity ratio, respectively. The production rate of frictional entropy also increments by more than 800% with reducing Darcy number and porosity.

中文翻译：

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增加滑移速度和多孔块的微通道中非牛顿纳米流体的数值研究

摘要 近年来，微流体传热的研究引起了研究人员的极大兴趣。在改善微器件热性能的研究中，已经研究了纳米流体、几何校正和其他参数的使用。除了研究冷却系统的传热外，近年来对这些系统的热力学第二定律的研究也得到了广泛的研究。本研究利用有限体积法（SIMPLE算法）研究了壁面温度分布变化的微通道中非牛顿纳米流体的热力学第二定律和传热、多孔块的有无和滑移速度。调查。非牛顿纳米流体包含水-CMC作为基流体和体积分数为3%和4%的TiO2纳米粒子。当前的研究在雷诺数 (10-100) 和纳米颗粒体积分数 (3-4) 的两个部分中进行了审查。在第一部分，它研究了滑移速度的影响，并比较了具有不同滑移系数 (0-0.1) 的一阶和二阶模型对传热、流体流动、熵产生和火用损失的影响。结果表明，一阶滑移速度使平均努塞尔数增加2.02%~12.48%，二阶滑动速度增加1.91%~7.52%。此外，一阶和二阶滑移速度分别使摩擦熵的产生率最大降低了 76.2% 和 67.43%。热熵和火用损失的速率产生表现出随雷诺数变化的行为。在第二部分中，达西数 (5 × 10−3–5 × 10−5)、孔隙度 (0.75–0. 95) 和热导率 (1-15) 与一阶滑移速度进行了检查。通过分别降低、降低和提高达西数、孔隙率和热导率比，努塞尔数局部增加。随着达西数和孔隙率的降低，摩擦熵的产生率也增加了 800% 以上。